Calorie Calculator

Calculate your daily calorie needs using the Mifflin-St Jeor equation. Find calories for weight loss, maintenance, and muscle gain based on your activity level.

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How Calories Are Calculated

This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating calorie needs.

Mifflin-St Jeor Equation

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

Activity Multipliers

Sedentary (×1.2): Little to no exercise, desk job
Light (×1.375): Light exercise 1-3 days/week
Moderate (×1.55): Moderate exercise 3-5 days/week
Active (×1.725): Hard exercise 6-7 days/week
Very Active (×1.9): Very hard exercise, physical job

Calorie Goals

Weight Loss

A 500 calorie deficit per day leads to approximately 1 pound of weight loss per week. The calculator shows a moderate 500-calorie deficit.

Weight Gain

A 500 calorie surplus per day supports muscle gain when combined with resistance training. Larger surpluses may lead to excess fat gain.

Important Considerations

These are estimates—individual metabolism varies by 10-15%
Muscle mass increases calorie needs; body fat decreases them
As you lose weight, recalculate your needs every 10-15 pounds
Consult a healthcare provider before starting any diet program

Common Food Calorie Reference

Chicken breast (3 oz cooked): 165 calories
White rice (1 cup cooked): 200 calories
Brown rice (1 cup cooked): 218 calories
Egg (large): 72 calories
Banana (medium): 105 calories
Slice of bread: 70-80 calories
Tablespoon of olive oil: 120 calories
Apple (medium): 95 calories

Metabolic Adaptation

When you eat in a calorie deficit for extended periods, your body adapts by lowering its metabolic rate — a survival mechanism. This is why weight loss often stalls after several weeks despite the same diet. To counter this:

Use moderate deficits (500 cal/day) rather than aggressive ones
Include resistance training to preserve muscle mass
Consider periodic "diet breaks" (eating at maintenance for 1-2 weeks)
Recalculate your TDEE as your weight changes

Practical Calorie Tracking

Read the serving size on nutrition labels first — it affects every number on the label. A bag of chips may list 150 calories per serving, but contain 3 servings. Use a food scale for accuracy; volume measurements (cups, tablespoons) can vary by 20% or more depending on how you scoop.

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Frequently Asked Questions

How many calories should I eat to lose weight?

Eat about 500 calories a day below your maintenance calories (TDEE) to lose roughly 1 pound a week. Do not go below 1,200 calories a day for women or 1,500 for men without medical supervision, because very low intakes make it hard to meet nutrient needs and are difficult to sustain.

How many calories does a moderately active woman need per day?

A 35-year-old woman who is 165 cm, weighs 68 kg and is moderately active needs about 2,130 calories a day. Mifflin-St Jeor gives BMR = (10 x 68) + (6.25 x 165) - (5 x 35) - 161 = 1,375 kcal, and multiplying by the moderate activity factor of 1.55 gives a TDEE of about 2,132 kcal.

What is the difference between BMR and TDEE?

BMR is the calories your body burns at complete rest to keep breathing and circulation going. TDEE is BMR multiplied by an activity factor, from 1.2 for sedentary to 1.9 for very active, plus digestion. A sedentary person and an active athlete of the same weight can differ by 1,000 or more calories a day.

How accurate are calorie calculators?

The Mifflin-St Jeor equation, considered the most accurate, estimates BMR within about 10 percent for most people. Individual metabolism varies by up to 15 percent, and tools give different numbers because they use different equations such as Harris-Benedict or Katch-McArdle. Treat any result as a starting point and adjust after a few weeks of tracking weight.